ANALYSIS OF POLAR CHOLESTEROL OXIDATION-PRODUCTS - EVALUATION OF A NEW METHOD INVOLVING TRANSESTERIFICATION, SOLID-PHASE EXTRACTION, AND GAS-CHROMATOGRAPHY
Hg. Schmarr et al., ANALYSIS OF POLAR CHOLESTEROL OXIDATION-PRODUCTS - EVALUATION OF A NEW METHOD INVOLVING TRANSESTERIFICATION, SOLID-PHASE EXTRACTION, AND GAS-CHROMATOGRAPHY, Journal of agricultural and food chemistry, 44(2), 1996, pp. 512-517
Monitoring cholesterol oxidation products is important in the evaluati
on of the potential health risks associated with lipid oxidation. In t
he present study, a method allowing quick and reliable analysis of pol
ar cholesterol oxidation products was evaluated. After Soxhlet-lipid e
xtraction, the fat was transesterified under mild conditions, thereby
minimizing degradation and allowing determination of the free and este
rified cholesterol oxides. Sample fractionation was achieved with amin
opropyl solid phase extraction cartridges and a stepwise elution with
hexane, hexane/methyl tert-butyl ether, and acetone to separate polar
cholesterol oxides from cholesterol and other lipid products. Further
analysis of the trimethylsilyl derivatives was performed by gas chroma
tography with detection by flame ionization or mass spectrometry. A ph
ytosterol oxide such as sitosterol alpha-epoxide (24 alpha-ethyl-5 alp
ha,6 alpha-epoxycholestan-3 beta-ol) was employed for the first time a
s an internal standard for the quantification of cholesterol oxides in
foodstuffs of animal origin.